Timed Switch Project
Planet Holloway Physics
Objective:
To build a timer that starts with a switch and then starts the next students device at a set time later. This device will be used to demonstrate several physics concepts.
Materials:
Do not use - anything expensive, anything made specifically for a clock or timer.
Do use - recycled materials from home or inexpensive craft and hardware type items. Examples are paper towel tubes, toothpicks, cardboard, poster board, craft sticks, wire, rubber bands, plastic soda bottles, dowels, etc.
Procedure:
Construct a timed switch that meets the following criteria:
· The device will be no bigger than 18” x 18” x 24”(high)
· The device must be activated by having a small mass (like a marble) from another device land on the switch
· The switch may be mechanical and/or electrical (battery powered)
· The switch must initiate the timer that will run for either 20, 30, or 40 seconds
· The device must then after the designated time, drop a small mass (typically a marble or ball bearing) 3” to 5” in order to start the next device
· The device should demonstrate no less than three different physics topics covered to date, but no more than two topics from any one section. (Mechanics, fluids, oscillations/springs, thermodynamics, waves, sound, light, or you use concepts we will cover later in the year including electricity and magnetism, but you will have to learn these on your own).
· The device must be capable of being reset for another run in under 90 seconds
Attach labels in appropriate locations on the device to draw attention to your relevant topics
Attach an explanation that explains how the device works and explains the relevant concepts. Think about the plaques found in museums and science centers that explain the demonstration equipment. This “plaque” must be thorough, but succinct. Be sure your plaque teaches the observer the physics principles and does not simply state them. If you have more than three then you may need an additional plaque. Illustrations are highly recommended. Formulas are encouraged, but don’t list something without explaining it.
Scoring: (required components)
10 points possible – labels correctly placed and justified (three concepts required)
30 points possible – interesting, concise and education “plaque”
10 points possible – no bigger than 18” x 18” x 24”(high)
10 points possible – starts by a small mass landing on the switch (this should “stick out from your project so that the previous team’s device can activate yours. It is recommended that you pick a group to receive and to deliver your object from/to in order to make your two/three devices align properly before the grading session.
30 points possible – device times precisely 20, 30 or 40 seconds (within 1 second), every 2 seconds after the first second away from the desired time is 3 points off
10 points possible – device starts another device by dropping a small mass 3” to 5” away
30 points possible – device builders correctly explain three different concepts that the device demonstrates
Bonus features: (non-required components)
5 points possible – device lasts for 30 seconds (within one second)
10 points possible – device lasts for 40 seconds (within one second)
5 points possible – uses four different concepts that are correctly explained by the builders
10 points possible – use five different concepts that are correctly explained by the builders
20 points possible – runs flawlessly twice. Your device must be started by a small mass in the parameters detailed above, run for the correct time (within one second), and then drop a mass capable of starting the next project. Then, your device must be completely reset within 90 seconds and run as above one more time.
Notes:
The timing device is not graded on appearance, but on performance and on the understanding of the scientific principles involved. Do not spend time making it “pretty”, but work on the bonus features and discussing where and why the labels belong where they do. Also, the “plaque” should basically explain to a middle school student how the device demonstrates physics concepts and the importance of each concept.
Score sheet Names:
Include with project
Device Name – ______
Category / Points possible / Self Grade / Points EarnedLabels (correct, neat, interesting)
(ex. gravity – not interesting, too simple) / 10
Plaque (teaches as well as describes) / 30
Correct size (within one inch) / 10
Starting switch / 10
Correct time – 20 s, 30 s, 40 s (circle)
1 sec off -3, 3 sec = -6, 5 sec = -9, etc / 30
Starts next device / 10
Builder knowledge of concepts (detailed, correct and relevant explanation) / 30
Sub total / 130
Bonus points / Not required
“Precisely” 30 seconds (within 1 sec) / 5
“Precisely” 40 seconds (within 1 sec) / 10
Correctly uses and explains four concepts / 5
Correctly uses and explains five concepts / 10
Device runs twice flawlessly / 20
Total / 130
Good Luck!